hollow sound from amp???

yeah i just got an alpine mrp-320 and it was working good, cutting out everynow and then cuz of heating problems but i just thought that wuz cuz it wuz new. but now it cuts out at less than have of the volume it used to and when it is playing everything sounds hollow and kind of echos. i dont know what the deal is it just happened all of a sudden. i wasnt even playing it loud and it started doin that. any idea what it is?